heater core question

[truckinwagen]

I just ditched the HVAC box in my 85 GTI because it was all screwed up, and weighs a ton.

now I have a bare heater core under the dash, and I intend to build a box with a fan to connect to the windshield defrost vent.

my question is, does the stock heater system actually blow air through the heater core(looks very restrictive) or does it just blow air past the heater core(around it)

I could not tell from the mangled mess that came out from under my dash.

I thought I would just put a small fan on the back of the heater core(like a little radiator fan), but I am not sure if it will be able to blow through it as the fins are really close together, should I put the core in a box with a fan to blow air past it?

thanks for any input,
-Owen

[theman53]

If I remember it goes straight through the core. I think it goes through both the heater core and the evapcore for a/c cars as I ditched my evap on my 83 gti and it seems like I have 2x the flow.

[truckinwagen]

ok, so the air actually goes through the core?
it just seems very restrictive to me.

[rabbitman]

ok, so the air actually goes through the core?
it just seems very restrictive to me.

Yup, just like how the rad fan works.